class TypeMap {
    val instances = mutableMapOf<KClass<*>, Any>()

    operator fun <T : Any> set(type: KClass<T>, instance: T) {
        instances[type] = instance
    }

    inline operator fun <reified T : Any> get(type: KClass<T>): T {
        return instances[type] as T
    }
}


fun main() {
    val tm = TypeMap()
    tm[String::class] = "a" // does not compile if key/value types mismatch
    val value:String = tm[String::class] // same as above
    println(value) // a
    println(value is String) // true
}